Arthritis is a condition describing inflammation of a joint, and applies to over 100 diseases that have been identified to date. Most of these diseases fall into one of two categories: degenerative arthritis, such as osteoarthritis, or inflammatory arthritis, such as rheumatoid arthritis. Symptoms of most types of arthritis include pain, stiffness, and swelling in the joint. The specific cause of each type of arthritis varies, but many are thought to have both an environmental and genetic component. Effective treatment is dependent on the type of arthritis, and most often includes a combination of exercise, physical therapy, and medication.